Abstract: A matched set of fluorescent dyes is provided, wherein each dye of the set is capable of covalent attachment to a protein and wherein each of the dyes has a molecular structure and a charge that is matched one with the other, such that relative electrophoretic mobility of a protein labeled with one dye of the set is the same as the electrophoretic mobility of the protein labeled with a different dye of the set. The matched set comprises at least two different fluorescent dyes of formula: wherein n is 1, 2, or 3; Z1 and Z2 independently represent the carbon atoms necessary to complete a phenyl or naphthyl ring system; one of groups R1 and R2 is a target bonding group; remaining group R1 or R2 is selected from —(CH2)4—W or —(CH2)r—H; group R3 is hydrogen, except when either R1 or R2 is —(CH2)r—H, in which case R3 is W; and W is selected from sulphonic acid and sulphonate.

Abstract: Nucleoside analogues or base analogues having structure (I), where X=O or NH or S, Y=N or CHR6 or CR6, W=N or NR6 or CHR6 or CR6 or S, n=1 or 2; each R6 is independently H or O or alkyl or alkenyl or alkoxy or aryl or a reporter moiety; where necessary (i.e. when Y and/or W is N or CR6 where R6 is not O) a double bond is present between Y and W or W and W, and Q is H or a sugar or a sugar analogue or a nucleic acid backbone or backbone analogue.

Abstract: Nucleoside analogues have structure (2) wherein Q is H or a sugar moiety or sugar analogue or a modified sugar or a nucleic backbone or backbone analogue, W is an alkylene or alkenylene chain of 0-5 carbon atoms, any of which may carry a substituent R8, X is O or N or NR12 or CR10, X′ is O or S or N, provided that when X′ is O or S, then X is C, Y is CH or N, R6 is NH2 or SMe or SO2Me or NHNH2, each of R7 and R8 is independently H or F or alkyl or alkenyl or aryl or acyl or a reporter moiety, R12 is independently H or alkyl or alkenyl or aryl or acyl or a reporter moiety, and R10 is H or ═O or F or alkyl or aryl or a reporter moiety.

Abstract: Nucleoside analogues or base analogues having structure (1), where X=O or NH or S, Y=N or CHR6 or CR6, W=N or NR6 or CHR6 or CR6 or S, n=1 or 2; each R6 is independently H or O or alkyl or alkenyl or alkoxy or aryl or a reporter moiety; where necessary (i.e. when Y and/or W is N or CR6 where R6 is not O) a double bond is present between Y and W or W and W, and Q is H or a sugar or a sugar analogue or a nucleic acid backbone or backbone analogue.

Abstract: Nucleotide or base analogues having structure (3) or (4) wherein X═O or NH or S and each R6 is independently H or alkyl or alkenyl or alkoxy or aryl or a reporter moiety.